Genetic testing for hereditary colorectal cancer

Hereditary Cancer Screening and Outcomes at an Urban Safety-Net Hospital

PURPOSE

Patients with hereditary cancer syndromes (HCS) have a high lifetime risk of developing cancer. Historically underserved populations have lower rates of genetic evaluation. We sought to characterize demographic factors that are associated with undergoing HCS evaluation in an urban safety-net patient population.

METHODS

All patients who met inclusion criteria for this study from 2016 to 2021 at an urban safety-net hospital were included in this analysis. Inclusion criteria were pathologically confirmed breast, ovarian/fallopian tube, colon, pancreatic, and prostate cancers. Patients also qualified for hereditary breast and ovarian cancers or Lynch syndrome on the basis of National Comprehensive Cancer Network guidelines. Institutional review board approval was obtained. Demographic and oncologic data were collected through retrospective chart review. Univariable and multivariable logistic regression models were constructed.

RESULTS

Of the 637 patients included, 40% underwent genetic testing. Variables associated with receiving genetic testing on univariable analysis included patients living at the time of data collection, female sex, Latinx ethnicity, Spanish language, family history of cancer, and referral for genetic testing. Patients identifying as Black, having Medicare, having pancreatic or prostate cancer, having stage IV disease, having Eastern Cooperative Oncology Group (ECOG) prognostic score ≥1, having medium or high Charlson comorbidity index, with current or previous cigarette use, and with previous alcohol use were negatively associated with testing. On multivariable modeling, family history of cancer was positively associated with testing. Patients identifying as Black, having colon or prostate cancer, and having ECOG score of 2 had significantly lower association with genetic testing.

CONCLUSION

Uptake of HCS was lower in patients identifying as Black, those with colon or prostate cancer, and those with an ECOG score of 2. Efforts to increase HCS testing in these patients will be important to advance equitable cancer care.

Colorectal cancer disease profile and treatment patterns at an urban tertiary hospital in Rwanda

Background

The incidence of colorectal cancer (CRC) in sub-Saharan Africa (SSA) is rising, due to improving cancer registration efforts on one hand and an increasing westernisation of diets and lifestyle on the other as well as increasing rates of comorbidities.

Methods

We present data for the clinical characteristics, pathology, treatments received, and survival outcomes of patients diagnosed with CRC at King Faisal Hospital (KFH) between January 2019 and May 2023. KFH is an urban tertiary hospital in Rwanda that provides chemotherapy and surgery to cancer patients. The data were extracted from electronic medical records, imaging and histopathology reports from the patient's time of diagnosis. We plotted Kaplan-Meier estimation of survival, defined as the time from presentation to death, within the study period (2019-2023).

Results

Seventy-four patients diagnosed with CRC with complete information were identified in the KFH oncology records. The mean age at diagnosis was 54.6 years, with ages ranging between 22 and 81 years. At diagnosis, 24 (32.4%) patients were less than 50 years old and 29 (39.2%) were females. The rectum (36.5%) was the most common tumour location, and 58.1 tumours were left-sided. Most patients presented with Stage III (41.9%) or IV (35.1%) disease. Adenocarcinoma was the most common histological type (98.6%) including adenocarcinoma not otherwise specified (NOS) (86.5%), mucinous adenocarcinoma (10.8%), signet ring cell carcinoma (1.4%) and followed by squamous cell carcinoma (1.4%). In terms of treatment, 19 (25.7%) patients received only chemotherapy, 43 (58.1%) patients received neo-adjuvant or adjuvant chemotherapy, 9 (12.2%) of patients received both neo-adjuvant and adjuvant chemotherapy, 49 patients (66.2%) underwent surgery and 17 (23%) patients also received radiation. At the end of the follow up period, 63 (85.1%) patients remained in surveillance, 10 (13.5%) patients died, and 1 (1.3%) patient was lost to follow up. Mean overall survival was 45.5 (SD ± 2.0) months.

Conclusion

CRC patients presented at an advanced stage and required complex treatment regimens at KFH. Further epidemiologic and molecular research is needed to characterise CRC incidence and presentation at a national level in Rwanda as increasing westernisation continues to change the face of CRC in urban areas of SSA.

Genetic Testing and/or Counseling for Colorectal Cancer by Health Insurance Type

Genetic testing is increasingly used in clinical practice to assist with the diagnosis of genetic diseases and/or provide information about disease risk, and genetic counseling supports patient understanding of test results before and/or after genetic testing. Therefore, access to genetic testing and counseling is important for patient care. Health insurance coverage is a major determinant of access to health care in the United States. Uninsured individuals are less likely to have a regular source of health care than their insured counterparts. Different health insurance types and benefits also influence access to health care. Data on the association of health insurance and uptake of genetic testing and/or counseling for cancer risk are limited. Using data from the National Health Interview Survey, we examined the uptake of genetic testing and/or counseling for colorectal cancer (CRC) risk by health insurance type. We found that only a small proportion of individuals undergo genetic testing and/or counseling for CRC risk (0.8%), even among subgroups of individuals at risk due to family or personal history (3.7%). Insured individuals were more likely to undergo genetic testing and/or counseling for CRC risk, particularly those with Military and Private insurance plans, after adjusting for various demographic, socioeconomic, and health risk covariates. Further investigations are warranted to examine potential disparities in access and health inequities.

The FamilyTalk randomized controlled trial: patient-reported outcomes in clinical genetic sequencing for colorectal cancer

As genetics gains favor in clinical oncology, it is important to address patient concerns around confidentiality, privacy, and security of genetic information that might otherwise limit its utilization. We designed a randomized controlled trial to assess the social impact of an online educational tool (FamilyTalk) to increase family communication about colorectal cancer (CRC) risk and screening. Of 208 randomized participants, 149 (71.6%) returned six-month surveys. Overall, there was no difference in CRC screening between the study arms. Privacy and confidentiality concerns about medical and genetic information, reactions to genetic test results, and lifestyle changes did not differ between arms. Participants with pathogenic or likely pathogenic (P/LP) and variant of uncertain significance (VUS) results were more likely than those with negative results to report that the results accurately predicted their disease risks (OR 5.37, p = 0.02 and OR 3.13, p = 0.02, respectively). This trial demonstrated no evidence that FamilyTalk impacted patient-reported outcomes. Low power, due to the limited number of participants with P/LP results in the overall sample, as well as the short follow-up period, could have contributed to the null findings.

Knowledge, Awareness, and Perception of Genetic Testing for Hereditary Disorders Among Malaysians in Klang Valley

Genetic testing aids patients in making important decisions in the prevention, treatment, or early detection of hereditary disorders. Low awareness of the importance of genetic testing contributes to the increase in the incidence of hereditary disorders. This study aims to explore the knowledge, awareness, and perception of genetic testing for hereditary disorders among local residents of the Klang Valley, Malaysia, and the potential variables that influence their understanding of genetic testing. A survey was conducted in different municipalities of the Klang Valley through self-administered questionnaire assessing the public's knowledge, awareness, and perception of genetic testing. Overall, the results revealed adequate knowledge and positive awareness of genetic testing, in which both were influenced by the respondent's educational level (P < 0.001), field of study (P < 0.001), and status of heard or unheard of genetic testing (P < 0.001). The perception of genetic testing was generally positive and influenced by the respondent's differences in age (P < 0.016), educational level (P < 0.001), field of study (P < 0.001), and status of heard or unheard of genetic testing (P < 0.001). Although positive responses were obtained, ~20.2% of the respondents had never heard of genetic testing. Of the respondents, 24.5% were unwilling to undergo genetic testing, with 25.1% believing that genetic testing tampers with nature and 18% believing that it opposes religion and their beliefs. Such attitude calls for the need to conduct programs to eliminate any misconception, as well as to educate the public to lessen any perceived misunderstanding of the concepts of genetic testing.

Using chatbots to screen for heritable cancer syndromes in patients undergoing routine colonoscopy

BACKGROUND

Hereditary colorectal cancer (HCRC) syndromes account for 10% of colorectal cancers but remain underdiagnosed. This feasibility project tested the utility of an artificial intelligence-based chatbot deployed to patients scheduled for colonoscopy to identify HCRC risk factors, educate participants about HCRC and obtain consent to genetic testing as an extension of genetic counselling of appropriate subjects. Genetic counsellor (GC) and genetic counselling assistant (GCA) time spent per subject was also measured.

METHODS

Patients scheduled for colonoscopy at Cleveland Clinic were invited via electronic medical record patient portal or letter prior to colonoscopy with a link to a chatbot administering the Colon Cancer Risk Assessment Tool (CCRAT) to screen for HCRC syndromes. Those with ≥1 positive response to a CCRAT question received chatbot-deployed genetic education and the option to receive genetic testing. An order for a 55-gene pan-cancer panel was placed for those consenting, and the subject had blood drawn on the day of colonoscopy. Results were disclosed by a GC or GCA by telephone. Subject demographics, progression through the chat, responses to CCRAT, personal and family history, genetic test results and communication with the subject were recorded. Descriptive statistics and two-tailed unpaired t-test and Fisher's exact test were used.

RESULTS

506/4254 (11.9%) initiated and 487 (96.2%) completed the chat with the chatbot. 215 (44.1%) answered 'yes' to ≥1 CCRAT question and all completed pretest education. 129/181 (71.3%) subjects who consented completed testing, and 12 (9.3%) were found to have a germline pathogenic variant. Per subject, the GC spent a mean of 14.3 (SD 7.3) and the GCA a mean of 19.2 (SD 9.8) minutes.

CONCLUSION

The use of a chatbot in this setting was a novel and feasible method, with the potential of increasing genetic screening and testing in individuals at risk of HCRC syndromes.

Targeted deep-intronic sequencing in a cohort of unexplained cases of suspected Lynch syndrome

Lynch syndrome (LS) is caused by germline defects in DNA mismatch repair (MMR) pathway, resulting in microsatellite instability (MSI-H) and loss of immunohistochemical staining (IHC) of the respective protein in tumor tissue. However, not in all clinically suspected LS patients with MSI-H tumors and IHC-loss, causative germline alterations in the MMR genes can be detected. Here, we investigated 128 of these patients to possibly define new pathomechanisms. A search for large genomic rearrangements and deep-intronic regulatory variants was performed via targeted next-generation sequencing (NGS) of exonic, intronic, and chromosomal regions upstream and downstream of MLH1, MSH2, MSH6, PMS2, MLH3, MSH3, PMS1, and EPCAM. Within this cohort, two different large rearrangements causative for LS were detected in three cases, belonging to two families (2.3%). The sensitivity to detect large rearrangements or copy number variations (CNV) was evaluated to be 50%. In 9 of the 128 patients (7%), previously overlooked pathogenic single-nucleotide variants (SNV) and two variants of uncertain significance (VUS) were identified in MLH1, MSH2, and MSH6. Pathogenic aberrations were not found in MLH3, MSH3, and PMS1. A potential effect on regulation was exerted for 19% of deep-intronic SNVs, predominantly located in chromosomal regions where the modification of histone proteins suggests an enhancer function. In conclusion, conventional variation analysis of coding regions is missing rare genomic rearrangements, nevertheless they should be analyzed. Assessment of deep-intronic SNVs is so far non-conclusive for medical questioning.

Universal tumor screening for Lynch syndrome: perspectives of Canadian pathologists and genetic counselors

Universal screening of all newly diagnosed colorectal cancer tumors can identify individuals at high risk for Lynch syndrome (LS), a hereditary cancer syndrome predisposing carriers to increased risk of colorectal, endometrial, and other cancers. To inform planning of a universal tumor screening program for LS in our jurisdiction, we undertook online surveys of Canadian pathologists and genetic counselors to describe existing tumor screening programs. Online surveys were hosted on SurveyMonkey between October 2016 and March 2017. Fifty-three pathologists and 66 genetic counselors completed surveys (total n = 119). While attitudes towards tumor screening were positive, considerable variability was observed in the existence of tumor screening, test ordering criteria, and practices. Most respondents indicated consent was not obtained for tumor screening nor were educational materials provided to patients; however, opting out of additional mutation testing in the event of a positive tumor screen was endorsed. Results add to the growing literature on providers' perspectives on population-based tumor screening programs and inform ways to offer these. Findings highlight the need to develop methods of patient education that allow meaningful opt-out decisions. The variability we observed also suggests the need for national standards and guidance on tumor screening for LS.

N_LyST: a simple and rapid screening test for Lynch syndrome

Aims

We sought to use PCR followed by high-resolution melting analysis to develop a single closed-tube screening panel to screen for Lynch syndrome. This comprises tests for microsatellite instability (MSI), MLH1 methylation promoter and BRAF mutation.

Methods

For MSI testing, five mononucleotide markers (BAT25, BAT26, BCAT25, MYB, EWSR1) were developed. In addition, primers were designed to interrogate Region C of the MLH1 promoter for methylation (using bisulphite-modified DNA) and to test for mutations in codon 600 of BRAF. Two separate cohorts from Nottingham (n=99, 46 with MSI, 53 being microsatellite stable (MSS)) and Edinburgh (n=88, 45 MSI, 43 MSS) were tested.

Results

All the cases (n=187) were blind tested for MSI and all were correctly characterised by our panel. The MLH1 promoter and BRAF were tested only in the Nottingham cohort. Successful blinded analysis was performed on the MLH1 promoter in 97 cases. All MSS cases showed a pattern of non-methylation while 41/44 cases with MSI showed full methylation. The three cases with MSI and a non-methylated pattern had aberrations in MSH2 and MSH6 expression. BRAF mutation was detected in 61% of MSI cases and 11% of MSS cases.

Finally, 12 cases were blind screened by using the whole panel as a single test. Of these, five were identified as MSS, four as MSI/non-LS and three as MSI/possible LS. These results were concordant with the previous data.

Conclusion

We describe the Nottingham Lynch Syndrome Test (N_LyST). This is a quick, simple and cheap method for screening for Lynch syndrome.

Family health history: an essential starting point for personalized risk assessment and disease prevention

Family health history (FHH) information is well established as a basis for assessing a patient's personal disease risk, but is underutilized for diagnosis and making medical recommendations. Epidemiological and genetic information have heightened the value of FHH to an individual's health. This has motivated the development of new FHH collection tools and strategies for family members, but will require greater awareness and knowledge by both patients and practitioners. FHH will be increasingly important as genomic data become a mainstay of medical diagnostics, since in many cases, a medically important FHH results from lineage-specific genetic variants. The impact of complementary FHH and genomic information will drive the pursuit of personalized and precise targeting of treatments and interventions aimed at maintaining patient health.

Analysis of current testing practices for biallelic MUTYH mutations in MUTYH-associated polyposis

MUTYH-associated polyposis (MAP) is an autosomal recessive syndrome caused by biallelic mutations in the base excision repair gene MUTYH. Owing to potential limitations in the MAP testing strategy and testing criteria, it is possible that MAP is being under-identified both genotypically and phenotypically. To determine whether full sequencing of MUTYH would increase clinical sensitivity over a founder mutation (FM) strategy, a retrospective analysis of two datasets from a commercial clinical laboratory was performed. The first cohort contained 1522 individuals who received MUTYH analysis for two FMs with subsequent full-gene sequencing. Eighty-five biallelic individuals were identified; 47 carried two FMs, 17 carried one FM and one mutation identified on full sequencing, and 21 carried biallelic mutations identified only on full sequencing. The second cohort contained 921 patients with colorectal cancer <50 years and <10 reported colorectal adenomas who had undergone MUTYH mutation testing. In this cohort, 19 of 921 (2.1%) individuals were identified as biallelic MUTYH carriers. Of these, 13 did not have a personal or family history of polyps and would not have met guidelines for MUTYH testing. These results suggest that individuals with biallelic MUTYH mutations are under-ascertained based on both genotype and phenotype under current standard testing practices.

Evaluation of clinical criteria for the identification of Lynch syndrome among unselected patients with endometrial cancer

Clinical criteria, primarily young age of cancer onset and family history of signature cancers, have been developed to identify individuals at elevated risk for Lynch syndrome with the goals of early identification and cancer prevention. In 2007, the Society of Gynecologic Oncology (SGO)-codified criteria for women presenting with gynecologic cancers. These criteria have not been validated in a population-based setting. For 412 unselected endometrial cancers, immunohistochemical expression of DNA mismatch repair proteins and MLH1 methylation were assessed to classify tumors as sporadic or probable Lynch syndrome (PLS). In this cohort, 10.5% of patients were designated as PLS based on tumor testing. The sensitivity and specificity of the SGO criteria to identify these same cases were 32.6% [95% confidence interval (CI), 19.2-48.5] and 77% (95% CI, 72.7-81.8), respectively. With the exception of tumor location in the lower uterine segment, multivariate analysis of clinical features, family history, and pathologic variables failed to identify significant differences between the sporadic and PLS groups. A simplified cost-effectiveness analysis demonstrated that the SGO clinical criteria and universal tissue testing strategies had comparable costs per patient with PLS identified. In conclusion, the SGO criteria successfully identify PLS cases among women with endometrial cancer who are young or have significant family history of signature tumors. However, a larger proportion of patients with PLS who are older and have less significant family history are not detected by this screening strategy. Universal tissue testing may be necessary to capture more individuals at risk for having Lynch syndrome.

Informed consent to microsatellite instability and immunohistochemistry screening for Lynch syndrome

OBJECTIVE

Routine microsatellite instability and immunohistochemistry screening of colorectal cancers can assist in identifying a significant proportion of cancers attributable to Lynch syndrome. This article considers whether it is necessary to obtain patient informed consent for microsatellite instability and immunohistochemistry screening.

RESULTS

Although microsatellite instability screening examines genetic features of a tumor, it lacks several important characteristics that typically mandate formal informed consent to genetic testing. Microsatellite instability screening describes discrete tissue samples and does not provide information about the rest of the patient's body or germline. In contrast, immunohistochemistry screening is a proteomic test that may reveal information about the patient's germline. As such, immunohistochemistry screening can be viewed as similar to other forms of genetic testing, in which explicit patient consent is regarded as an ethical prerequisite.

CONCLUSION

There is no ethical requirement to obtain explicit informed consent for microsatellite instability screening of colorectal tumor samples for Lynch syndrome. There is support for obtaining patient consent to immunohistochemistry testing, given its similarities with other genetic analyses for which informed consent is typically deemed necessary. Regardless of which screening test is used, it is important to prepare patients and their families for the possibility of a positive screening test.

Determining the frequency of de novo germline mutations in DNA mismatch repair genes

BACKGROUND

Carriers of a germline mutation in a DNA mismatch repair (MMR) gene--that is, persons with Lynch syndrome--have substantially high risks of colorectal (CRC), endometrial, and several other cancers. The proportion of carriers who have de novo mutations (not inherited from either parent) is not known. This study reports a case series of de novo mutations in MMR genes and estimates the frequency of de novo mutation in MMR genes using the Colon Cancer Family Registry.

METHODS

Screening for germline MLH1, MSH2, MSH6, and PMS2 mutations was performed for all incident CRC cases recruited from cancer registries (population based probands) displaying microsatellite instability (MSI) or loss of expression of MMR genes by immunohistochemistry (IHC) and probands with CRC in multi-case families recruited from clinics (clinic based probands), regardless of MSI or IHC status. All relatives of probands with a pathogenic mutation who donated a blood sample underwent testing for the mutation identified in the proband.

RESULTS

Of 261 probands (202 clinic based, 59 population based) with MMR gene mutations for whom it was possible to determine the origin of the mutation, six (2.3%, 95% CI 0.9% to 5.0%) were confirmed as de novo, and the remaining 255 (97.7%, 95% CI 95.0% to 99.1%) were inherited. Of the de novo mutation carriers, three were clinic based probands (1.5%, 95% CI 0.3% to 4.5%) and three were population based probands (5.1%, 95% CI 1.2% to 14.5%). Two were in MLH1, three in MSH2, and one in MSH6.

CONCLUSION

De novo MMR gene mutations are uncommon causes of Lynch syndrome.

How to manage a patient with multiple adenomatous polyps

Adenomatous polyps are found on screening colonoscopy in 22.5% to 58.2% of the adult population and therefore represent a common problem. Patients with multiple adenomatous polyps are of unique interest because a proportion of these patients have an inheritable form of colorectal cancer. This article discusses the history and clinical features, genetic testing, surveillance, and treatments for the condition.

Genetic counseling considerations in the evaluation of families for Lynch syndrome--a review

Lynch syndrome is the most common hereditary colorectal cancer syndrome and the most common cause of hereditary endometrial cancer. Identifying and evaluating families for Lynch syndrome is increasing in complexity due to the recognition that: family history-based clinical criteria lack sensitivity and specificity; genetic testing for Lynch syndrome continues to evolve as understanding of the molecular mechanisms underlying it evolves; and the Lynch syndrome phenotype encompasses multiple organ systems and demonstrates overlap with other hereditary cancer syndromes. This document is a summary of considerations when evaluating individuals and families for Lynch syndrome, including information on cancer risks, diagnostic criteria, tumor and genetic testing strategies, and the management of individuals with this condition.